@BlaineBug Is she getting a stabilitrak warning?

See refenced TSBs, especially 18-NA-161.

I heard you the first time. If she doesn't have stabilitrak symptoms then this is the wrong topic.

Please don't be so salty - I believe I was instrumental in the creation of TSB 20-NA-212 which I do not believe it related to her concerns posted here recently. No one had really ever experienced the issue I was describing in great detail as I perused the internet and posted about it on various forums. So if I have something helpful to provide I'll do so, which is a lot more helpful than telling someone to post a new thread about it - who cares.

However I do believe TSB 18-NA-161 does in fact directly relate to her steering jerks - her vehicle is a 2015 as well which is very early build, just in the timeframe where a lot of owners with 2014-2015/2016 model year Silverados and Sierras experienced the same issue with Ground #G218 being pinched between the firewall or top of dash and some sort of an insulation pad.

As for her loss of brakes it is possible the vacuum pump is to blame, as I also heard some of the early build vacuum pumps were quick to require replacement! Service Bulletin PIT5361 also outlines this braking problem - take a look here, and 2015 Tahoe is also part of the affected vehicles! https://static.nhtsa.gov/odi/tsbs/20...57667-3895.pdf

Now all she has to do is print out the 2 TSB's and 1 Service Bulletin and take them to a mechanic of her choice, and describe the issues, and I believe we'll find that there may be two "coincidental" yet separate issues occuring at the same time. UNLESS the ground wire mentioned in TSB 18-NA-161 also affects braking performance somehow.

Nobody is salty. I'm trying to get this car owner the best help possible, and I think the best way is for her to post a dedicated topic, instead of getting buried in this unrelated one.

If you or anyone else wishes to avoid the tips and recommendations I have made regarding such a problem, that's up to the end-user, and I won't sweat about it.